A wind turbine generator is an apparatus in which a rotor head provided with turbine blades rotates by receiving the force of wind and power is generated by a generator driven by utilizing this rotation.
The above-described rotor head is mounted at an end of a nacelle installed on a wind turbine tower (hereinafter, referred to as “tower”) in such a manner as to allow yawing, and the rotor head is supported thereon in such a manner as to allow rotation about a substantially horizontal lateral rotation axis.
In general, the above-described wind turbine tower often employs a steel monopole that employs a cylindrical shell and has a structure in which a base plate provided at the bottom end of the tower shell is secured to a steel-reinforced concrete base with anchoring bolts. Accompanying equipment, for example, an elevator, a ladder, cables, a stage, etc., is installed inside such a tower, and therefore, in order to support the accompanying equipment in the tower, tower-internal-equipment brackets (hereinafter, referred to as “brackets”), which are welded to internal wall surfaces of the tower shell, are provided.
FIG. 16 is a partial sectional view, showing an example of an internal structure of a tower shell 10 in a conventional monopole-type steel tower.
The illustrated tower shell 10 has a structure in which a desired height is achieved by joining a plurality of cylindrical shells 11. Accordingly, flanges 12 are attached at both ends of each cylindrical shell 11 by means of butt welding BW, and the individual cylindrical shells 11 are connected at the flange portions 12 of adjacent cylindrical shells 11 and are joined with bolts/nuts 13. With regard to the cylindrical shells 11, plate members are cylindrically shaped and end portions thereof are connected by means of butt welding.
In addition, brackets 14 are attached at appropriate locations on internal walls of the cylindrical shells 11 by means of fillet welding FW, for example, as with the illustrated brackets 14a, 14b, and 14c. Reference signs 15a and 15b in the figure indicate the tower internal equipment.
Other known bracket support structures include those in which, for example, magnets and adhesive are used, as disclosed in the following patent literature, in which case the fillet welding is not applied to the internal walls of the cylindrical shells.